Kids’ Bike Buying Advice From a Mechanic: Brakes & Tires

Brakes and Tires, Paired

Plenty of bicycle components will not work together, down to fitment. 29” wheels do not fit 26” frames and forks. It is impossible to force a 30.9mm O.D. dropper post into a 27.2 I.D. seat tube. Mix-maxing Shimano’s LinkGlide and HG+ drivetrain components is a no-go.

In that sense brakes and tires are universally inter-compatible. But anyone who has thrown a semi-slick onto the back of their DH bike without recalibrating their digits, or even downsizing the rear rotor, will agree that it is good to put a bit more thought into combinations.

Locking up a pair of Racing Ralphs or Aspens on an XC race rig with some SRAM Maven 1.1 brakes squeezing 203mm rotors is not ideal. And I would say the same about kiddo combinations I have seen a few times – riding down trails with Kenda Small Block 8 tires trying to modulate a hand-me-down pair of ShiRAMano 4-piston brakes.

The good news is that when it comes to 20” and 24” wheeled bikes the options for mountain bike tires are very limited. That is, tires that roll well up and across but offer excellent braking confidence when descending. Even in the world of 26” tires – and on grom bikes 26” really is not dead –overchoice is nonexistent thanks to a lack of good options.

Assumptions

As I previously noted in Gears & Shocks , this piece is assuming a certain budget either in buying a new grom rig or upgrading a used bike that has already been purchased. However, I want to recognize that it is more than possible for a kid to fall in love with mountain biking on a 1994 CCM Ice ‘MEGA OVERSIZE’ bike with bent forks, seized thumb-shifters, warped-to-wavy steel rims, and tires and brake pads made of the hardest rubber known to humankind. Or, you know, a less specific example from the same vein.

I hope that the absence of current geometry, hydraulic brakes, or tubeless tires is not keeping anyone – growing kid or grown-up kid – from trying mountain biking. At the same time, I recognize that progression to a certain level of trail is much more fun, and at some point, significantly safer, with a certain level of equipment.

There is an old, pre-meme even, joke that if you introduce your kids to mountain biking, they will never have any money to spend on drugs. Buying bike stuff certainly motivated me to get a job as a teenager and absorbed all my disposable income at the time.

One-Finger Braking

Braking with one finger is better because it leaves the rest of them free to hold on to our handlebar. It is sound logic and at some point, every rider makes the transition but groms with tiny digits trying to ride sustained downhills on tiny wheels may choose 2-finger braking at first.

This was my daughter’s experience with v-brakes and disc brakes up to the 24” wheel size where she started 1-finger braking until her hands became tired and then switched to two. The difference in control was notable. The solution here ended up being the same as what I would prescribe to an adult in the same boat, which was to upsize the front rotor.

My kid only weighed a bit more than 60lbs at the time and is riding 4-piston SRAM Guide brakes which, jokes aside, are plenty powerful for lighter riders in many situations. It simply came down to finger power.

SRAM Guide Brakes

Money-no-object, either a Hayes brake with their SFL (small finger lever) blades or a Magura setup with their HC lever blades would be a great light-action choice for kids. Shimano 4-piston ServoWave brakes with the pistons cheated in a bit and the reach set close to the bar can also be an excellent choice.

That said, most of the groms I know are on SRAM Guide brakes for the simple reasons that Guide, and G2, brakes frequently ship as original equipment on mountain bikes, and a significant number of riders upgrade to more powerful stoppers. If you live somewhere with steep, or even steepish, trails and have been riding for any length of time then you know someone with a pair of Guide or G2 brakes in a box that you can trade for a bag of beans or a six-pack.

They are easy to work on, and with rotors trued up and the pistons cheated a bit closer to the discs than the stock setup (by depressing the brake with a thinner-than-rotor-sized spacer between the pads) the reach and pull can work very well for those extra-extra small hands.

Budget-wise, a lot of the cheap hydraulic brakes that ship with kids, and commuter, bikes do not hold up to a significant amount of use, but a used set of Guides will be plug-and-play. The same goes for cable-actuated disc brakes. These can work very well for some applications, especially the nicest quality cable-actuated discs with regular attention, but the self-adjusting pad wear and pressure of a hydraulic system are superior for mountain biking.

If you do buy a kids’ bike with cable-actuated discs, start mentioning to any of your friends with Guide/G2 brakes that they need a fresh set of full-on super-stoppers. On the fence between otherwise equal models with v-brakes versus cable disc brakes and have no plans to upgrade? In most cases, kids are better served by the v-brake bike with lighter action and simpler adjustment. Especially for lower-angle fair-weather riding.

Cold Weather Considerations

Comfort is always a concern when riding with kids. I carry extra clothing and snacks and, though seldom a consideration, I am always prepared to pull the chute early to ensure there’s excitement about the next ride.

As someone who used to have no issue riding in the cold and wet with aluminum lever blades, but now finds that it is the one place where carbon fiber is worth every ounce of gold to upgrade. My grom is very fortunate in that when our friend Penny upgraded her brakes she hooked us up with her old Guides sporting levers made from plastic-fantastic but before then we both noticed a cold & wet comfort improvement from Lizard Skins DSP lever grips .

The DSP lever grips ship in double-pairs, so enough grips to do two bikes, for US$13. They seem expensive for what they are, but I found them to be a fantastic value in terms of logging more grom-miles in the winter months. My experiments with bodging a homemade solution from leftover grip tape were not great. They are not a magic bullet for frozen, sore, and un-dexterous digits, but they make enough of a difference that I just bought a fresh set to put on my bike that will be running aluminum lever blades this winter.

Tubeless + Minions

I am not, nor have I ever been, a tubeless evangelist for many cycling applications. There is the cost and the ongoing maintenance (topping up sealant, cleaning valves). Plus, for some riders, a loss of support without a tube pushing the tire bead against the rim, the addition of inserts, or at least a more supportive tire choice.

Sure, with properly supportive sidewalls or inserts, it is nice to be able to grab some extra traction by running less air pressure without the risk of pinch flatting. On Plus+ tires, like the front of my Waltworks V2, and on fat-bikes I have found it impossible to balance the awful basketball bouncing effect versus flats with tubes. I would much rather plug a punctured tubeless tire on the trail than pull my wheels off to change tubes.

I run tubeless on my mountain bikes and my groad/commuter but with the addition of CushCore inserts on all my off-road bikes. On my fair-weather pavement parade machine where traction is not a concern, I am on the fence whether the ride quality will improve with running sealant and a tubeless tire.

Most folks who recognize the potential negatives will still appreciate the traction and rolling improvements that Tubeless offers for offroad riding, but I also have no beef with all the folks who have tried it and gone back to faff-free butyl and changing a few punctured tubes a year.

Where I do become an evangelist of tubeless tires is for kids. How much of a pusher am I? On my daughter’s 20” Early Rider, now my nephew’s, with non-tubeless tires and non-tubeless rims I piled on the rim tape until the interface between bead & hook was sufficient to air up with a floor pump.

The difference in traction and ride quality are enormous. I air the tires (20” and 24” Maxxis DHF folding bead) down to about 14psi for improved climbing grip and the perfect amount of sidewall support for a 60-70lb rider in janky terrain. I always recommend bracketing tire pressure for your rider and terrain, but that is a good starting point and significantly softer than the same rider would be running tubes without experiencing pinch flats.

I am not a yellow-label fanboy, and my bicycles are currently shod with a mix of Schwalbe, Bontrager, and Specialized rubber. But if there was only one mountain bike tire that every rider had to use for every application I do not know that we could do better than a pair of Maxxis DHFs.

The DHF rolls fast enough, brakes well enough in a vast range of conditions, and in the 2.4” sizes that my daughter and nephew ride they do not do anything weird. I do wish that Maxxis offered their folding 24” tires in MaxxGrip compound as well as MaxxTerra as we would run MaxxGrip up front here on the North Shore. I wish the 20” size came with the same tubeless-ready bead and EXO sidewall as the 24” does. Then again, I also wish that Specialized made their relatively high-value Butcher T7 and T9 tires in 20”, 24”, and 26” sizes.

There are very few good options for climbing and descending technical mountain bike terrain, but Maxxis makes one good enough tire for 20” and 24” and that is awesome. Schwalbe makes the Big Betty in a 20x2.25” and 24x2.4” but compared to a DHF it rolls along like a full blocky chunker without adding enough braking performance downhill to warrant the difference. In my mind the Knobby Nic, whilst far from my favourite Schwalbe tire, would have been the better candidate for the extra-small-size mountain bike tire treatment.

Many a grom getaway vehicle comes with Vee Rubber tires and I have had mixed results airing these up tubeless and with their performance grip-wise, but a Crown Gem or Flow Snap is still a massive improvement over the tires coming on many kids’ rigs. Especially once converted to tubeless.

Contact Points Matter

Tires are our contact points with the sport surface and brakes are a key aspect of how we control our tires. It has been my experience that combined with geometry these components will make a significantly larger difference to the mountain bike experience than suspension – front, rear, none, budget, or boutique – or any drivetrain upgrade. Grips, pedals, and a saddle are the only items more personally important.

The good news is that, in my experience, while good rubber is expensive, our kids are significantly smoother than we are so tires tend to only need replacing when they are legitimately worn out from use. Likewise, the high-performance Galfer brake pads in my daughter’s Guide brakes last a very long time. Her rotors, particularly the rear rotor, are always in need of straightening due to their proximity to the ground, but that is a story for another day.